1. Field of the Invention
The invention relates to a method for sorting plant material units. Furthermore, the invention relates to a computer readable medium, having computer readable instructions stored thereon for performing, when executed by a processor, a method for sorting plant material units. Finally, the invention relates to an apparatus for sorting plant material units.
2. Description of the Related Art
In many horticultural and agricultural applications, plant material units are transferred multiple times to improve the yield. For example, for seedlings or sprouts it is important that sufficient growing space is available. Furthermore, underdeveloped plant material units are preferably removed at an early stage to use greenhouse space as efficiently as possible.
However, transfer of plant material units, such as seedlings or sprouts, may cause damage, not only to the plant material being transferred, but also to adjacent plant material units. Therefore, it is desirable to minimize the number of transfers, as well as keep the handling time for transfer as brief as possible.
International patent application WO2008/150903 describes a system and method for sorting seeds based on identified phenotypes of the seeds. The seeds are provided in a bulk seed hopper and after dispersion onto a feed platform transferred into a seed picking reservoir. Seeds are then captured out of the seed picking reservoir and placed into a seed tray. The seed tray is imaged so that image data is available for all seeds within the seed tray. Subsequently, the image data is processed to identify seed characteristics or phenotypic traits. Based on the identified seed characteristics or phenotypic traits, the seeds are assigned to a predetermined class, and then selectively removed from the seed tray and sorted to a selected seed repository, each seed repository being designated to receive only seeds identified to have a particular one of the predetermined classes. The system and method of WO2008/150903 comprises many transfers. Furthermore, the type of transfers involves bulk transfer of seeds (e.g. on the feed platform and parallel transfer of seeds by means of a funnel under the influence of gravity from the seed tray to a selected repository), as well as bulk storage of seeds (e.g. in the seed hopper, in the seed picking reservoir, as well as in the seed repositories designed to a predetermined class). Although such handling may be suitable for seeds, transfer and/or storage of seedlings or sprouts in such a way would result in high probability of plant material damage, which is undesirable.
US-patent application 2013/0021469 describes a method and system for seed classification using spectral analysis to determine the existence of a seed structure. The method and system discuss a pattern recognition technique that may improve classification of the seeds being analyzed. US2013/0021469 does not discloses any method or system for sorting plant material units, such as seedling or sprouts.
US-patent application 2012/0020531 relates to a method of automated image analysis of an organic polarized object. In the method, the precise location and orientation of an organic polarized object, such as a seed or bulb, is identified to enable pick-up and placement by a robot